I have had the same issues with PD15 over the past week. I got the same messages as the original poster, but tried to overcome the issue by logging out of my Google account. However, after getting the Script error messages, I then got the following after clicking ok:
'Couldn't sign you in
This browser or app may not be secure. Learn more
Try using a different browser. If you’re already using a supported browser,
you can refresh your screen and try again to sign in.'
,,,which gets me nowhere.
Is upgrading to PD16 or other the best option? I tried uploading one of the videos I saved on to PD15 but couldn't upload, but it's only showing my uploaded cases on to YouTube, not the one outstanding.